The Moving Ahead for Progress in the 21^st Century Act, an infrastructure spending bill signed into law in 2012 by President Obama, included a provision allowing sponsors of defined benefit plans to apply higher interest rates to assess future liabilities.

The pension smoothing provision was written as a “pay for” to fund the spending bill.

By allowing sponsors to use the 25-year average of the corporate bond yield, instead of lower near-term rates, plans were allowed to estimate lower liability values, in turn requiring lower annual contributions to plans.

Lower contribution rates meant less money corporations could write off at tax time, translating to more revenue the feds could use to fund infrastructure spending.

But pension smoothing also has the effect of artificially improving pensions’ funded status, say critics of the tactic. According to the SOA, the impact of pension smoothing on plan funding is considerable.

When applying lower, “unsmoothed” interest rates to assess liabilities, the number of fully funded plans drops from 89 percent to 28 percent.

What’s more, pension smoothing vastly affects the number of plans that contribute enough to maintain their unfunded liability and maintain a 7-year funding pace, or the amount of annual contributions needed to close a funding gap over seven years. By law, those two benchmarks are used to assess a plan’s annual minimum contribution rate.

Using smoothed interest rates, 8 percent of plans with an unfunded liability contributed enough to at least maintain funding ratios in 2014. Only 3 percent of unfunded plans fell short of that benchmark.

But when applying unsmoothed rates, almost half of the 72 percent of plans with an unfunded liability did not contribute enough to maintain funding ratios in 2014.

And 55 percent of plans did not contribute enough to close funding gaps within seven years.

In 2014, the smoothed corporate bond rate used to project liabilities was around 6.5 percent, compared to the unsmoothed rate of about 4.75 percent.

The overall pension liability for single employer plans was $1.9 trillion in 2014 when using the higher smoothed rate. As a lot, the plans were 98 percent funded with $30 billion in unfunded pension obligations.

But when applying the lower unsmoothed rate, total liabilities jump to $2.4 trillion, with a funded rate of 91 percent, and $218 billion in unfunded liabilities, according to the SOA.